Lighting can be an important consideration in some applications, such as livestock production. As an example, so-called “long day” lighting practices have been proposed to promote increased daily milk production from cows. Some research also suggests, for example, that poultry development behaviors can be influenced by lighting intensity, color, or time schedule. For example, infrared lighting may promote aggression in chickens, while too much darkness might lead to fearfulness.
In general, “poultry” can refer to domesticated fowl raised for meat or eggs. Typical examples of poultry can include chickens, turkeys, ducks, geese, emus, ostriches or game birds. In some cases, poultry are raised in a poultry house. An example poultry house could be 40 feet wide and 600 feet long, with a ceiling that is eleven feet high. For so-called “broilers,” young chickens raised for their meat, one research study found that a schedule of intermittent lighting resulted in decreased fat deposition and improved feed conversion efficiency relative to a continuous lighting environment. (See Rahmi, G., et al., “The Effect of Intermittent Lighting Schedule on Broiler Performance,” Int'l. J. Poultry Sci. 4 (6): 396-398 (2005), the entire contents of which are incorporated herein by reference).
Various types of lighting have been employed in livestock production facilities. Livestock lighting systems that have been used include incandescent, fluorescent, and more recently, LEDs (light emitting diodes).
LEDs are becoming widely used devices capable of illumination when supplied with current. Typically, an LED is formed as a semiconductor diode having an anode and a cathode. In theory, an ideal diode will only conduct current in one direction. When sufficient forward bias voltage is applied between the anode and cathode, conventional current flows through the diode. Forward current flow through an LED may cause photons to recombine with holes to release energy in the form of light.
The emitted light from some LEDs is in the visible wavelength spectrum. By proper selection of semiconductor materials, individual LEDs can be constructed to emit certain colors (e.g., wavelength), such as red, blue, or green, for example.
In general, an LED may be created on a conventional semiconductor die. An individual LED may be integrated with other circuitry on the same die, or packaged as a discrete single component. Typically, the package that contains the LED semiconductor element will include a transparent window to permit the light to escape from the package.